Science: Slow-acting poison deals locusts a double blow

A pesticide that not only kills locusts, but helps one of the locust's natural enemies at the same time, has been identified by a team of scientists in South Africa. Usually, pesticides kill both the target insect and its predators. Because the chemical delivers a double blow to the locusts, these insects may take longer to recover after a spraying, reducing the need to apply pesticide so frequently.

Roger Price and his colleagues from the Plant Protection Research Institute in Pretoria, South Africa, made their discovery while carrying out experiments in the Karoo. They were spraying brown locust nymphs (Locustana pardalina) with different amounts of deltamethrin, a synthetic pyrethroid, to see how the death rate of poisoned insects was affected by the weather.

When they applied 15 grams of deltamethrin per hectare, Price and his colleagues found that locusts sought shade in deep drifts under bushes. The researchers noticed that ...

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